The goal of research in this project is to identify the sources of difficulties in reading at the sentence level and to aid in meeting the goal of early identification of children who are likely to develop reading problems. Some of the problems are traceable to poor reader's inadequate skills in decoding words. If decoding is unreliable and slow, the integrative processes in reading connected text may be severely hampered, especially in sentence structures that stress working memory. But word decoding difficulty is not the whole problem. It has often been found that poor readers' comprehension difficulties occur not only in reading, but also extend to spoken language. This fact led us to study comprehension of syntactic structures that poor readers find difficult, and to develop a model that relates these problems to poor readers' limitations in phonological processing. It is important to distinguish between the possibility that poor reader's comprehension difficulties reflect a bottleneck in processing phonological information from the alternative possibility that the problems stem in part from a developmental lag in mastery of some syntactic structures. Experiments with children before and after literacy instruction begins are proposed to test between these possibilities. These will exploit recent techniques developed by members of this project that have proven successful in teasing apart syntactic competence from performance. Since our previous research largely supports the processing limitation interpretation of poor readers' comprehension failures, we propose experiments to test predictions of this hypothesis by investigating an act of reading as it is happening. Fluent readers and poor readers, children and adults, will be tested with on-line measures of sentence reading, including eye movement measures in order to identify the specific sites of reading difficulty for poor readers. Eye movement recording is the on-line method of choice for investigating reading disabilities because it is the only technique that allows reading to proceed unimpeded, permitting normal rates and levels of comprehension. It also has proven sensitivity for detecting even quite subtle effects of processing load associated with different, linguistic structures and contexts.